Nuclear power plant vertical jacking water taking and draining structure and construction method

Abstract

The invention relates to the technical field of nuclear power plant sea area water taking and draining engineering, in particular to a nuclear power plant vertical jacking water taking and draining structure and a construction method. The nuclear power plant vertical jacking water taking and draining structure comprises a steel casing, a vertical pipe assembly and a shield tunnel used for being communicated with a nuclear power plant water taking and draining device; the steel casing is vertically arranged and buried in a seabed, and the upper end of the steel casing extends out of the seabed; the shield tunnel extends below the lower end of the steel casing; a pipeline jacking hole is formed in the shield tunnel, and the pipeline jacking hole is formed below the lower end of the steel casing; the inner cavity of the steel casing is used for being filled with filler to replace a soil layer of a seabed in the steel casing. The vertical pipe assembly is used for being jacked out from the pipeline jacking hole, and penetrates out of the upper end of the steel casing after penetrating through the filler in the steel casing; the lower end of the vertical pipe assembly is used for being fixedly connected with a pipeline jacking hole. The upper end of the vertical pipe assembly is used for installing a water taking and draining head to form a water taking and draining channel.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear power plant sea area water intake and drainage engineering, and in particular to a nuclear power plant vertical jacking water intake and drainage structure and a construction method. Background Art

[0002] Considering that nuclear power plants require a large amount of cooling water to operate, nuclear power plants at home and abroad currently tend to use coastal or near-shore sites. With the increasing requirements of the country for marine protection in recent years, most of the nuclear power plants built in China have abandoned the conventional open channel drainage method and instead used tunnels to extend into deep water areas for drainage. That is, tunnels are built under the seabed to introduce deep seawater into the water intake pump room, or cooling water is discharged to the sea through tunnels.

[0003] After the tunnel is excavated from the land to the deep sea, the existing technology generally adopts the vertical jacking process inside the constructed tunnel to form the water intake and drainage outlet. The vertical jacking process is to reserve a jacking hole on the upper part of the completed tunnel, and use a jack to push the prefabricated riser pipe sections out of the main tunnel section by section from the jacking hole. After the top cover of the riser reaches the specified height, the cover is removed underwater by divers, and then the water intake / drainage head is installed to form the water intake / drainage outlet. However, this process has high requirements for the strata in the jacking area. When the rock strata in the jacking area are hard, the jacking operation of the riser is difficult to carry out due to insufficient jacking force in the vertical jacking construction in the tunnel and insufficient bearing capacity of the tunnel base; when the rock strata in the jacking area are soft soils such as silt, the stability of the riser during service life is difficult to guarantee. Summary of the invention

[0004] The present invention provides a vertical jacking drainage structure and construction method for a nuclear power plant, thereby solving the technical problems that in the prior art, a drainage outlet is formed by a vertical jacking process inside a constructed tunnel, the requirement for the stratum in the jacking area is high, and when the rock stratum in the jacking area is hard, the jacking operation of the riser is difficult to carry out due to insufficient jacking force in the vertical jacking construction in the tunnel and insufficient bearing capacity of the tunnel base; and when the rock stratum in the jacking area is soft soil such as silt, the stability of the riser during service is difficult to ensure.

[0005] The technical solution adopted by the present invention is: a vertical lifting drainage structure of a nuclear power plant, comprising a steel casing, a riser assembly and a shield tunnel for communicating with a drainage device of the nuclear power plant;

[0006] The steel casing is vertically arranged and buried in the seabed, and the upper end of the steel casing extends out of the seabed;

[0007] The shield tunnel extends to below the lower end of the steel casing; a pipeline jacking hole is opened on the shield tunnel, and the pipeline jacking hole is arranged below the lower end of the steel casing;

[0008] The inner cavity of the steel casing is used to fill the filling material to replace the soil layer of the seabed inside the steel casing;

[0009] The riser assembly is used to be lifted out from the pipeline lifting hole, pass through the filling material in the steel casing, and then pass out to the outside of the upper end of the steel casing; the lower end of the riser assembly is used to be fixedly connected to the pipeline lifting hole;

[0010] The upper end of the riser assembly is used to install a water intake and drainage head to form a water intake and drainage channel.

[0011] Through the construction of steel casing, the soil layer of the seabed is excavated and replaced by the filling material, and the filling material can be adjusted to a hardness suitable for the vertical jacking operation to achieve the technical effect of ensuring that the vertical jacking operation can be carried out smoothly and the stability of the riser assembly during the service life. The existing technology solves the problem that the vertical jacking process is used inside the constructed tunnel to form the water intake and drainage outlet, and the requirements on the stratum in the jacking area are high. When the rock stratum in the jacking area is hard, the jacking operation of the riser is difficult to carry out due to insufficient jacking force of the vertical jacking construction in the tunnel and insufficient bearing capacity of the tunnel base; when the rock stratum in the jacking area is soft soil such as silt, the stability of the riser during the service life is difficult to ensure.

[0012] Furthermore, a mounting opening is provided at the top of the riser assembly, and the mounting opening is used to install a cap to close the top of the riser assembly during the jacking process;

[0013] The installation opening is also used for installing the drainage head that replaces the cap to form a drainage channel.

[0014] Based on the vertical lifting and drainage structure of a nuclear power plant provided by the present invention, the present invention also provides a construction method of the vertical lifting and drainage structure of a nuclear power plant, comprising the following steps:

[0015] Step 1: vertically burying a steel casing in the seabed, and extending the upper end of the steel casing out of the seabed;

[0016] Step 2: digging out the soil layer of the seabed in the steel casing;

[0017] Step 3: Filling the inner cavity of the steel casing with filler;

[0018] Step 4: construct a shield tunnel, so that the shield tunnel extends to below the lower end of the steel casing; and open a pipeline jacking hole on the shield tunnel, so that the pipeline jacking hole is located below the lower end of the steel casing;

[0019] Step 5: Use a vertical jacking method to jack up the riser assembly from the pipeline jacking hole, pass through the filling material in the steel casing, and then pass out to the outside of the upper end of the steel casing, and fix the lower end of the riser assembly to the pipeline jacking hole;

[0020] Step 6: Install a drainage head at the upper end of the riser assembly to form a drainage channel.

[0021] Furthermore, the step 1 includes the following sub-steps:

[0022] The buried area of ​​the steel casing and the surrounding seabed soil layer are reinforced with compacted sand piles;

[0023] The steel casing is vertically buried in the seabed soil layer of the burying area, and the upper end of the steel casing is extended out of the seabed.

[0024] By reinforcing the buried area of ​​the steel casing and the surrounding seabed soil layer with compacted sand piles, the stability of the steel casing can be improved, and during the vertical jacking construction of the riser assembly, the steel casing can be prevented from being skewed due to the squeezing of the filling material, thereby affecting the vertical jacking construction.

[0025] In another technical solution, the step 1 includes the following sub-steps:

[0026] excavating a foundation pit at a preset position on the seabed, and laying slopes around the foundation pit according to a preset slope ratio;

[0027] The steel casing is vertically buried at the bottom of the foundation pit, and the elevation of the upper end of the steel casing is higher than the elevation of the original seabed surface;

[0028] The space around the steel casing and between the side slope of the foundation pit is backfilled with riprap to form a backfill layer, and the top elevation of the backfill layer is made the same as the elevation of the original seabed surface.

[0029] By backfilling the space around the steel casing and the slope of the foundation pit with rocks to form a backfill layer, the stability of the steel casing can be improved. During the vertical jacking construction of the riser assembly, the steel casing can be prevented from tilting due to the squeezing of the filling material, thereby affecting the vertical jacking construction.

[0030] Furthermore, when the space between the periphery of the steel casing and the side slope of the foundation pit is backfilled with riprap, the riprap is symmetrically placed around the steel casing.

[0031] By placing the riprap symmetrically around the steel casing, it is possible to avoid the riprap being displaced and high points appearing, and it is also possible to avoid the steel casing being tilted due to uneven force on the surrounding areas.

[0032] Furthermore, in step 2, drilling construction is carried out in the steel casing, drilling to below the lower end of the steel casing, and making the height difference between the bottom of the borehole and the lower end of the steel casing not less than a preset height difference, so as to dig out the soil layer of the seabed in the steel casing.

[0033] Furthermore, in step 4, the height difference between the upper side surface of the portion of the shield tunnel located below the lower end of the steel casing and the lower end of the steel casing is made smaller than the preset height difference.

[0034] Furthermore, in step 3, the filler includes calcium-based clay and medium-coarse sand, and the filler is filled into the inner cavity of the steel casing to form a medium-coarse sand layer and a calcium-based clay layer in sequence from top to bottom in the steel casing.

[0035] Furthermore, the construction method of the vertical lifting and drainage structure of a nuclear power plant also includes:

[0036] Step 7: Inject cement slurry into the backfill material between the inner side surface of the steel casing and the outer side surface of the riser assembly for reinforcement.

[0037] Furthermore, in step 1, the steel casing is vertically buried in the seabed, and the depth to which the lower end of the steel casing is embedded in the strongly weathered rock layer is within a preset depth range.

[0038] The vertical lifting drainage structure and construction method of a nuclear power plant provided by the present invention have at least the following technical effects or advantages:

[0039] 1. Through the construction of steel casing, the soil layer of the seabed is excavated and replaced by the filling material, and the filling material can be adjusted to a hardness suitable for the vertical jacking operation to achieve the technical effect of ensuring that the vertical jacking operation can be carried out smoothly and the stability of the riser assembly during the service life can be guaranteed; the technical problem that the vertical jacking process is used inside the constructed tunnel to form the intake and drainage outlets in the prior art, and the requirements on the stratum in the jacking area are high. When the rock stratum in the jacking area is hard, the jacking operation of the riser is difficult to carry out due to insufficient jacking force of the vertical jacking construction in the tunnel and insufficient bearing capacity of the tunnel base; when the rock stratum in the jacking area is soft soil such as silt, the stability of the riser during the service life is difficult to guarantee.

[0040] 2. By reinforcing the buried area of ​​the steel casing and the surrounding seabed soil layer with compacted sand piles, the stability of the steel casing can be improved, and during the vertical jacking construction of the riser assembly, the steel casing can be prevented from being skewed due to the squeezing of the filling material, thereby affecting the vertical jacking construction.

[0041] 3. By backfilling the space around the steel casing and the slope of the foundation pit with stones to form a backfill layer, the stability of the steel casing can be improved. During the vertical jacking construction of the riser assembly, the steel casing can be prevented from tilting due to the squeezing of the filling material, thereby affecting the vertical jacking construction.

[0042] 4. By placing the riprap symmetrically around the steel casing, it is possible to avoid the riprap being displaced and high points appearing, and it is also possible to avoid the steel casing being skewed due to uneven force around the steel casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the construction process of the vertical lifting and drainage structure of the nuclear power plant in the embodiment Figure 1 ;

[0044] Figure 2 This is the construction process of the vertical lifting and drainage structure of the nuclear power plant in the embodiment Figure 2 ;

[0045] Figure 3 This is the construction process of the vertical lifting and drainage structure of the nuclear power plant in the embodiment Figure 3 ;

[0046] Figure 4 This is the construction process of the vertical lifting and drainage structure of the nuclear power plant in the embodiment Figure 4 ;

[0047] Figure 5 This is the construction process of the vertical lifting and drainage structure of the nuclear power plant in the embodiment Figure 5 ;

[0048] Figure 6 This is the construction process of the vertical lifting and drainage structure of the nuclear power plant in the embodiment Figure 6 ;

[0049] Among them: 1-steel casing, 2-riser assembly, 3-shield tunnel, 4-filling material, 5-compacted sand pile, 6-foundation pit, 7-backfill layer;

[0050] 6.1—Slope. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention:

[0052] Embodiment 1:

[0053] like Figure 6 As shown, this embodiment 1 provides a vertical lifting drainage structure for a nuclear power plant, including a steel casing 1, a riser assembly 2, and a shield tunnel 3 for communicating with a drainage device of the nuclear power plant;

[0054] The steel casing 1 is vertically arranged and buried in the seabed, and the upper end of the steel casing 1 extends out of the seabed;

[0055] The shield tunnel 3 extends to below the lower end of the steel casing 1; a pipeline jacking opening is opened on the shield tunnel 3, and the pipeline jacking opening is arranged below the lower end of the steel casing 1;

[0056] The inner cavity of the steel casing 1 is used to fill the filling material 4 to replace the soil layer of the seabed inside the steel casing 1;

[0057] The riser assembly 2 is used to be lifted out from the pipeline lifting hole, and after passing through the filling material 4 in the steel casing 1, it passes out to the outside of the upper end of the steel casing 1; the lower end of the riser assembly 2 is used to be fixedly connected to the pipeline lifting hole;

[0058] The upper end of the riser assembly 2 is used to install a drainage head to form a drainage channel.

[0059] By constructing the steel casing 1 and using the filling material 4 to excavate and replace the soil layer of the seabed, the filling material 4 can be adjusted to a hardness suitable for the vertical jacking operation to achieve the technical effect of ensuring that the vertical jacking operation can be carried out smoothly and the stability of the riser assembly 2 during its service life. This solves the problem that in the prior art, the vertical jacking process is used inside the constructed tunnel to form the intake and drainage outlets, which has high requirements on the strata in the jacking area. When the rock strata in the jacking area are hard, the jacking operation of the riser is difficult to carry out due to insufficient jacking force in the vertical jacking construction in the tunnel and insufficient bearing capacity of the tunnel base; when the rock strata in the jacking area are soft soils such as silt, the stability of the riser during its service life is difficult to ensure.

[0060] Preferably, in this embodiment 1, a mounting opening is provided at the top of the riser assembly 2, and the mounting opening is used to install a cap to close the top of the riser assembly 2 during the jacking process;

[0061] The installation opening is also used to install a drainage head of a replacement cap to form a drainage channel.

[0062] Embodiment 2:

[0063] like Figures 1 to 6As shown, based on the vertical lifting and drainage structure of a nuclear power plant provided in Example 1, Example 2 further provides a construction method for the vertical lifting and drainage structure of a nuclear power plant, including the following steps:

[0064] Step 1: vertically bury the steel casing 1 in the seabed, and extend the upper end of the steel casing 1 out of the seabed;

[0065] Step 2: digging out the soil layer of the seabed in the steel casing 1;

[0066] Step 3: Filling the inner cavity of the steel casing 1 with a filler 4;

[0067] Step 4: construct the shield tunnel 3 so that the shield tunnel 3 extends to below the lower end of the steel casing 1; and open a pipeline jacking hole on the shield tunnel 3 so that the pipeline jacking hole is located below the lower end of the steel casing 1;

[0068] Step 5: Use the vertical lifting method to lift the riser assembly 2 out of the pipeline lifting hole, pass through the filling material 4 in the steel casing 1, and then pass out to the outside of the upper end of the steel casing 1, and fix the lower end of the riser assembly 2 to the pipeline lifting hole;

[0069] Step 6: Install a drainage head at the upper end of the standpipe assembly 2 to form a drainage channel.

[0070] Wherein, step 1 includes multiple implementation schemes, such as but not limited to:

[0071] Option 1:

[0072] Step 1 includes the following sub-steps:

[0073] The buried area of ​​the steel casing 1 and the surrounding seabed soil layer are reinforced with compacted sand piles 5;

[0074] The steel casing 1 is vertically buried in the seabed soil layer of the burying area, and the upper end of the steel casing 1 is extended out of the seabed.

[0075] By reinforcing the buried area of ​​the steel casing 1 and the surrounding seabed soil layer with compacted sand piles 5, the stability of the steel casing 1 can be improved, and during the vertical jacking construction of the riser assembly 2, it can be avoided that the steel casing 1 is skewed due to the squeezing of the filling material 4, thereby affecting the vertical jacking construction.

[0076] Option 2:

[0077] Step 1 includes the following sub-steps:

[0078] Excavating a foundation pit 6 at a preset position on the seabed, and laying slopes around the foundation pit 6 according to a preset slope ratio;

[0079] The steel casing 1 is vertically buried at the bottom of the foundation pit 6, and the elevation of the upper end of the steel casing 1 is higher than the elevation of the original seabed surface;

[0080] The space around the steel casing 1 and between the side slope 6.1 of the foundation pit 6 is backfilled with riprap to form a backfill layer 7, and the top elevation of the backfill layer 7 is made the same as the elevation of the original seabed surface.

[0081] By backfilling the space around the steel casing 1 and the side slope 6.1 of the foundation pit 6 with rocks to form a backfill layer 7, the stability of the steel casing 1 can be improved, and during the vertical jacking construction of the riser assembly 2, it can be avoided that the steel casing 1 is skewed due to the squeezing of the filling material 4, thereby affecting the vertical jacking construction.

[0082] Preferably, in this embodiment 2, Figures 1 to 3 As shown, step 1 includes the following sub-steps:

[0083] The buried area of ​​the steel casing 1 and the surrounding seabed soil layer are reinforced with compacted sand piles 5;

[0084] Excavate a foundation pit 6 in the buried area, and lay a slope around the foundation pit 6 according to a preset slope ratio;

[0085] The steel casing 1 is vertically buried at the bottom of the foundation pit 6, and the elevation of the upper end of the steel casing 1 is higher than the elevation of the original seabed surface;

[0086] The space around the steel casing 1 and between the side slope 6.1 of the foundation pit 6 is backfilled with riprap to form a backfill layer 7, and the top elevation of the backfill layer 7 is made the same as the elevation of the original seabed surface.

[0087] Preferably, in this embodiment 2, the preset slope ratio is 1:4.

[0088] Preferably, in this embodiment 2, Figure 4 As shown, when the space between the surroundings of the steel casing 1 and the side slope 6.1 of the foundation pit 6 is backfilled with riprap, the riprap is symmetrically placed around the steel casing 1.

[0089] By placing the riprap symmetrically around the steel casing 1, it is possible to avoid the riprap from being displaced and high points appearing, and it is also possible to avoid the steel casing 1 from tilting due to uneven force on the surrounding areas.

[0090] Preferably, in this embodiment 2, Figure 4 As shown, in step 2, drilling construction is carried out in the steel casing 1, drilling to below the lower end of the steel casing 1, and the height difference between the bottom of the borehole and the lower end of the steel casing 1 is not less than a preset height difference, so as to dig out the soil layer of the seabed in the steel casing 1.

[0091] Preferably, in this embodiment 2, Figure 6As shown, in step 4, the height difference between the upper side surface of the portion of the shield tunnel 3 located below the lower end of the steel casing 1 and the lower end of the steel casing 1 is made smaller than a preset height difference.

[0092] By making the height difference between the upper side surface of the portion of the shield tunnel 3 located below the lower end of the steel casing 1 and the lower end of the steel casing 1 smaller than the preset height difference, the upper side surface of the portion of the shield tunnel 3 located below the lower end of the steel casing 1 can directly contact the filling material 4, thereby ensuring that no seabed rock will remain between the upper side surface of the portion of the shield tunnel 3 located below the lower end of the steel casing 1 and the filling material 4, thereby ensuring that the riser assembly 2 does not need to pass through the seabed rock formation during the vertical jacking process, and can completely avoid the situation where the jacking operation is difficult due to insufficient jacking force when the strength of the seabed rock formation is relatively large.

[0093] Preferably, in this embodiment 2, in step 3, the filler 4 includes calcium-based clay and medium-coarse sand, and the filler 4 is filled into the inner cavity of the steel casing 1 to form a medium-coarse sand layer and a calcium-based clay layer in sequence from top to bottom in the steel casing 1.

[0094] Preferably, in this embodiment 2, the construction method of the vertical lifting drainage structure of a nuclear power plant further includes:

[0095] Step 7: Inject cement slurry into the backfill material between the inner side of the steel casing 1 and the outer side of the riser assembly 2 for reinforcement.

[0096] Preferably, in this embodiment 2, in step 1, the steel casing 1 is vertically buried in the seabed, and the lower end of the steel casing 1 is embedded into the strongly weathered rock layer at a depth within a preset depth range.

[0097] Preferably, in this embodiment 2, the preset depth range is 0.5 meter to 1 meter.

[0098] The vertical lifting drainage structure and construction method of a nuclear power plant provided by the present invention have at least the following technical effects or advantages:

[0099] 1. Through the construction of the steel casing 1, the soil layer of the seabed is excavated and replaced by the filling material 4. The filling material 4 can be adjusted to a hardness suitable for the vertical jacking operation to achieve the technical effect of ensuring that the vertical jacking operation can be carried out smoothly and the stability of the riser assembly 2 during the service life. The prior art solves the problem that the vertical jacking process is used inside the constructed tunnel to form the intake and drainage outlets, and the requirements for the strata in the jacking area are high. When the rock strata in the jacking area are hard, the jacking operation of the riser is difficult to carry out due to insufficient jacking force of the vertical jacking construction in the tunnel and insufficient bearing capacity of the tunnel base; when the rock strata in the jacking area are soft soils such as silt, the stability of the riser during the service life is difficult to ensure.

[0100] 2. By reinforcing the buried area of ​​the steel casing 1 and the surrounding seabed soil layer with compacted sand piles 5, the stability of the steel casing 1 can be improved, and during the vertical jacking construction of the riser assembly 2, the steel casing 1 can be prevented from tilting due to the squeezing of the filling material 4, thereby affecting the vertical jacking construction.

[0101] 3. By backfilling the space around the steel casing 1 and the slope 6.1 of the foundation pit 6 with stones to form a backfill layer 7, the stability of the steel casing 1 can be improved, and during the vertical jacking construction of the riser assembly 2, the steel casing 1 can be prevented from tilting due to the squeezing of the filling material 4, thereby affecting the vertical jacking construction.

[0102] 4. By placing the riprap symmetrically around the steel casing 1, it is possible to avoid the riprap from being displaced and high points appearing, and it is also possible to avoid the steel casing 1 from tilting due to uneven force on the four sides.

[0103] 5. By making the height difference between the upper side surface of the portion of the shield tunnel 3 located below the lower end of the steel casing 1 and the lower end of the steel casing 1 smaller than the preset height difference, the upper side surface of the portion of the shield tunnel 3 located below the lower end of the steel casing 1 can directly contact the filling material 4, thereby ensuring that no seabed rock will remain between the upper side surface of the portion of the shield tunnel 3 located below the lower end of the steel casing 1 and the filling material 4, thereby ensuring that the riser assembly 2 does not need to pass through the seabed rock during the vertical jacking process, and can completely avoid the situation where the jacking operation is difficult due to insufficient jacking force when the strength of the seabed rock is relatively large.

[0104] The above are only specific application examples of the present invention and do not constitute any limitation to the protection scope of the present invention. Any technical solutions formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the present invention.

Claims

1. A vertical lifting and drainage structure for a nuclear power plant, characterized in that: It includes steel casing, riser assembly and shield tunnel for connecting with the nuclear power plant water intake and drainage device; The steel casing is vertically arranged and buried in the seabed, and the upper end of the steel casing extends out of the seabed; The shield tunnel extends to below the lower end of the steel casing; a pipeline jacking hole is opened on the shield tunnel, and the pipeline jacking hole is arranged below the lower end of the steel casing; The inner cavity of the steel casing is used to fill the filling material to replace the soil layer of the seabed inside the steel casing; The riser assembly is used to be lifted out from the pipeline lifting hole, pass through the filling material in the steel casing, and then pass out to the outside of the upper end of the steel casing; the lower end of the riser assembly is used to be fixedly connected to the pipeline lifting hole; The upper end of the riser assembly is used to install a water intake and drainage head to form a water intake and drainage channel.

2. The vertical lifting and drainage structure for a nuclear power plant according to claim 1, characterized in that: The top end of the riser assembly is provided with an installation opening, and the installation opening is used to install a cap to close the top end of the riser assembly during the jacking process; The installation opening is also used for installing the drainage head that replaces the cap to form a drainage channel.

3. A construction method for a vertical lifting and drainage structure of a nuclear power plant according to any one of claims 1 to 2, characterized in that: The following steps are involved: Step 1: vertically burying a steel casing in the seabed, and extending the upper end of the steel casing out of the seabed; Step 2: digging out the soil layer of the seabed in the steel casing; Step 3: Filling the inner cavity of the steel casing with filler; Step 4: construct a shield tunnel, so that the shield tunnel extends to below the lower end of the steel casing; and open a pipeline jacking hole on the shield tunnel, so that the pipeline jacking hole is located below the lower end of the steel casing; Step 5: Use a vertical jacking method to jack up the riser assembly from the pipeline jacking hole, pass through the filling material in the steel casing, and then pass out to the outside of the upper end of the steel casing, and fix the lower end of the riser assembly to the pipeline jacking hole; Step 6: Install a drainage head at the upper end of the riser assembly to form a drainage channel.

4. The construction method of the vertical lifting and drainage structure of a nuclear power plant according to claim 3 is characterized in that: The step 1 includes the following sub-steps: The buried area of ​​the steel casing and the surrounding seabed soil layer are reinforced with compacted sand piles; The steel casing is vertically buried in the seabed soil layer of the burying area, and the upper end of the steel casing is extended out of the seabed.

5. The construction method of the vertical lifting and drainage structure of a nuclear power plant according to claim 3 is characterized in that: The step 1 includes the following sub-steps: excavating a foundation pit at a preset position on the seabed, and laying slopes around the foundation pit according to a preset slope ratio; The steel casing is vertically buried at the bottom of the foundation pit, and the elevation of the upper end of the steel casing is higher than the elevation of the original seabed surface; The space around the steel casing and between the side slope of the foundation pit is backfilled with riprap to form a backfill layer, and the top elevation of the backfill layer is made the same as the elevation of the original seabed surface.

6. The construction method of the vertical lifting and drainage structure of a nuclear power plant according to claim 5 is characterized by: When the space between the periphery of the steel casing and the side slope of the foundation pit is backfilled with riprap, the riprap is symmetrically placed around the steel casing.

7. The construction method of the vertical lifting and drainage structure of a nuclear power plant according to claim 3 is characterized in that: In step 2, drilling construction is carried out in the steel casing, drilling to below the lower end of the steel casing, and making the height difference between the bottom of the borehole and the lower end of the steel casing not less than a preset height difference, so as to dig out the soil layer of the seabed in the steel casing.

8. The construction method of the vertical lifting and drainage structure of a nuclear power plant according to claim 7, characterized in that: In step 4, the height difference between the upper side surface of the portion of the shield tunnel located below the lower end of the steel casing and the lower end of the steel casing is made smaller than the preset height difference.

9. The construction method of the vertical lifting and drainage structure of a nuclear power plant according to claim 3, characterized in that: In step 3, the filler includes calcium-based clay and medium-coarse sand, and the filler is filled into the inner cavity of the steel casing to form a medium-coarse sand layer and a calcium-based clay layer in the steel casing from top to bottom.

10. The construction method of the vertical lifting and drainage structure of a nuclear power plant according to claim 3, characterized in that: Also includes: Step 7: Inject cement slurry into the backfill material between the inner side surface of the steel casing and the outer side surface of the riser assembly for reinforcement.

Images